feat(retrieval): a record the operator names by number reaches the menu (#4796)

#4796 "A record the operator names by number reaches auto-inject only if
its wording happens to match". "yes go ahead with 4448" says which record
is meant, but a number means nothing to an embedding, so the prompt menu
filled with records resembling the words around it.

- record_refs.named_record_ids reads the operator's raw prompt, never the
  reply-enriched query:
  - `#N`, unless the word before it marks another numbering (PR, CI, rule,
    milestone, system, log...);
  - a bare number of 3 or more digits that opens the message, follows a
    reference word or continues a list one started;
  - never a quantity ("300 seconds"), a date, version, path or fenced code.
- Each id is resolved through the ACL check; trashed or inaccessible ids
  are dropped.
- A "Named in your message" block leads the menu: the kind, the System,
  the name and the opening of the body, or the seen pointer if the record
  is already on the ledger. It takes no share of top_k, and the semantic
  lines leave those ids out.
- The block is booked under the new `named_ref` source, registered as an
  unbidden lookup that is allowed to be quiet. A named id that also ranked
  counts as suppressed in the auto_inject row, so #3668's identity holds.
- Named records now arrive even when the search finds nothing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/scribe/services/retrieval_registry.py

@@ -137,6 +137,16 @@ POINTS: dict[str, Point] = dict([
        "the one line reserved for a preference at the prompt boundary"),
     _p("reuse_slot", UNBIDDEN, "the one line reserved for a reusable snippet"),
     _p("lesson_slot", UNBIDDEN, "the one line reserved for a lesson"),
+    # A LOOKUP, not a ranker (#4796): a record the operator named by number
+    # in the message, fetched by id. No score and no bar, so it writes no
+    # retrieval_logs row and no score-shaped warning can apply; its rows are
+    # in `note_usage_events`, where pull-through says whether naming a record
+    # is followed by opening it.
+    _p("named_ref", UNBIDDEN,
+       "a record the operator named by number, looked up directly",
+       expects_traffic=False,
+       quiet_because="speaks only when a message names a record by its id; "
+                     "a window in which none did is correctly silent here"),
     _p("rule_via_lesson", UNBIDDEN,
        "a rule reached through a lesson confirmed as an instance of it",
        expects_traffic=False,